Process of protecting metal articles heated by the combustion of powdered coal.



n Ans an WILLIAM P. BAR-BA, OFPHILADELPHIA, PENNSYLvANIA, ASSIGNOR TO THE MIDVALE PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENN- s'r EL COMPANY, OF sYLvANIA.

' PROCESS OF PROTECTING METAL ARTICLES HEATED BY THE COMBUSTION F POWDERED COAL.

NO Drawing.

To all whom it may concern: Be it known that I, WILLIAM a citizen of the United States, residing at Philadelphia,'county of Philadelphia, and State of Pennsylvania, .have invented a new and useful Improvement in Processes of Protecting Metal Articles Heated by the lombustion of Powdered Goal, of which the following is a full, clear, and exact description.

My invention relates to the process of burning powdered coal in a furnace containforging;

ing billets or other articles of metal to be heat-treated or to be heated preparatory to The known advantage of this process is that it supplies heat at a relatively low price. The processinvolves the deposition' of the ash upon the articles undergoing treatment, which has certain advantages in that it aifords a coating that acts to reduce oxidaton. The process, however, has 'certain deleterious effects upon the articles undergoing treatn'lent. Vhile the coatingof the articles with ash tends to reduce oxidation, the ash usually fails to fuse with the scale to such an extent as to form a perfectly satisfactory protective coating, which scale is not only therefore so great in depth;

as to involve a considerable loss of metal but often adheres so closely to the articles Specification of Letters latent.

Application fi led August 17, 1914. Serial No. 857,110.

. fusing point to an extent which would de- P. BARBA,

stroy the adherent properties of the modified ash. I have found that the maximum percentage of calcium carbonate that will serve to produce the desired effect is about .65 per cent. ofthe ash-forming constituents of the coal and the best results are produced .if the quantity added is'net over per cent. If calcium oxid is used I prefer to add about 25 per cent. of the weight of the ashforming constituents of the coal. The result is that not only is the scale thus formed comparatively thin, but its toughness and brittleness is so modified that it possesses weak adherent properties and can be readily removed before forging.

Having 'now fully described my invention, what I claim and desire to protect by Let ters Patent is:

The process of protecting metal articles in a furnace in which'the coal is burned in a powdered form, which consists in burning in a furnace containing such metal articles powdered coal mixed with an inorganic basic substance in a proportion to the weight of the ash forming constituents of the coal,

sufiicient to raise the melting point of the ash to the extent required to cause it to adhere to the billets and form a protective coating therefor to minimize scale and in suflicient to elevate such melting point to adegree which would destroy its adherent property, substantially as described.

In testimony of which invention, I have hereunto set my hand, at Philadelphia, on this 27th day ,of July, 1914.

'WILLIAM P. BARBA.

' Witnesses:

JosEPn ENTWISLE, ARTHUR KRON EMANN. 

